Now the smallest Particles of Matter may cohere by the strongest Attractions, and compose bigger Particles of weaker Virture.... There are therefore Agents in Nature able to make the Particles of Bodies stick together by very strong Attraction. And it is the Business of experimental Philosophy to find them out.

Opticks: Or, A Treatise of the Reflections, Refractions, Inflections and Colours of Light.... (ed. 1718)